Refrigerating apparatus



Jan. 5 1926.

, E. THOMSON REFRIGERATING APPARATUS Filed July 28, 1923 I: W M B a O HO W l 0 M WI W o WAA/l /WVVV .w 3 .2 Y

1 Invenfor ///20 7710 son Affornev p a-a 1m,-

UNITED STA Tas" fpi'rrm OFFICE.

nnmu riionson', orisw a arsco r'r", massacxusnr'rs. kssmnon or onmrnxnn1'0 7 JOHN A, immune, or mum, massacausmrs, am) ommnian TO alums. ii.

exam ner miw'ronvinmi, xn ssnqn'usn'ppsg pp i aaii nadmy 2:1,

To all-whom it nwycomemr. a

Be it known that I, T OMSON- 21" citizen .of I the United States,residing at Swampscott, in the. county .of and State. of- Massachusetts,have invented certain new and useful. Improvements in RefrigeratingApparatus, of which the following is a specification. The presentinventionrelates specifically torefrigerating apparatus, suitable [fordomestic needs, and which is of; the type wherein a liquid oflargelatent heat fof,

- vaporization such for example as .sul hur dioxide and its vapor fillthe spaces ,0 the iefrigerating apparatus, the said liquid being used.in very limited amount to secure advantages, to be afterward. pointedout. The system includes the usual elements of condensing pump andcondenser with 'a 1 cooler or evaporator for vaporizing a liquid gas inattaining refrigeration;

The objects ofthe invention may be" stated to be to provide an apparatusof low cost, and relatively low power consumption for a given output of'practical'cooling, pro- ,viding means for regulating in desirable waysthe applicationof the cooling to useful ends and at a rate depending onthe c'all of the apparatus for such cooling; to improve the constructionand kietails of 'the various elements of the apparatus rendering it morereliable in practice, and to provide further anefiective means" forconserving the c0oling'efi'ect by the provision of what I term aneffective cooling barrier between the evaporator or cooler and theoutside air, automatically regulating the access of heatto theevaporator in accordance with the needs. Thislast mentioned featureconstitutes, in fact, a negative heat. storage or storage of cold, as iti or nega-tivelieat oi' cooling provided for in niirnio nairiim mam.

1933; has iaiesea'fir esssum "the apparatus. .It will be evident [that"since the 7 consumption of ata time when its cost is the"least, o rwhen it is desired to fill inload at the station, and. the apparatus canbe removed from the system or shut down duringthe period of light loador the period of overload. In accordance with this idea,,it is desirablethatthe cooling effect oithe motor and condensing pump,

energy is generally that of an electric. motor, such powerwmay -bedrawn. from the mains together with the other appliances, besufficiently great to only require operation during, say, 'daytime, withthe shut-down during sleeping hours, so that in domestic serv ce tw llnotbe necessary to have the apparatus running during the night, which isa time at which even a slight amount of f noise wouldbe disturbing.Whilst .automaticregulation to permit predetermined rest periods of,compression follows efiectively from-.mv -1ce barrier, any conventionalfautomatic regulation (as by means of a thermostat, or'such like) may beadditionally employed if desired; With the system offcold storage hereinprovided. by means 'of the ice barrier, the pump, while workingcontinuously durin periods of light or" no demand for cooling, would bedoing substantiallyno work, as the amount of SO in the apparatus is so'small'in proportion to the -s paces therein that there ispractically nopressure rise. When, however, the ice barrier melts sufiiciently and.

there is a realdemand for cooling, the

refrigerant inlthe evaporator vaporizes, the

pressure in the spaces begins to and the pump has work, to; do andperforms this work automatically of buildingup the pres: sure again toworking value.

Instead ofusing a largelot of liquefied gas, it is po'ssible'with theapparatus of my invention to make use ofa smallest quantity. of liquid,according to' the interior.

capacity. of the whole apparatus, and so arrangetlierycle'that this sameliquidcaii be evaporated and condensed over and over again, without thenecessity for providing a reservoir or aconsiderable storage of used.This is important because in case of a leak of S0 a minimum of thisrefriger- "liquid SO ,--which is the case in sulphur dioxiderefrigerating machines heretofore ant is available for leakage. The ad-7' pump, whereby when the load is heavy the clearance of the piston fromits head is 7 greater than when the load is at a minimum,

=' efficiency 'in the motor.

passing from one to the. other condition. This is accomplished byinterposmg a slightly compressible spring between the piston and itsoperating connecting rod, which, at the same time, does away with thenecessity for any wrist pin bearing. since the swing of the connectingrod is taken care of by the flexibility of the spring connection to thepiston.

The motor which drives the pump is de-.

manded to be run in a closed space filled with sulphur dioxide gas, andit has to be constructed with as high efficiency as possible, and thisfor the reason that economy of power in such a device will amply pay forthe increased cost of obtaining better Connections to such motor are, asis usual in such cases, carried through the casing by insulatedbushingsin the latter, and there will usually be two wires and sometimesa third, either let in through separate bushings in the motor casing, orcombined in a cable, this, however, being unimportant and a well knownarrangement. To discharge heat from the motor and its casing, it canhave fins all over it or wherever it may befound best for conveying heattherefrom. These are constructions so well. known that it is notnecessary to elaborate them here. Referring to the drawings, Fig. 1represents a side elevation, mostly in section, of the apparatus of myinvention; Fig. 2 represents a modification of the so-called coolingbarrier or low pressure cooling circuit for increasing the overallefficiency of the apparatus; Fig. 3 represents an enlarged section ofthe mechanism for automatically limiting the movement of the compressionpiston in accordance with the variations in pressure of therefrigerating vapor; Fig. i represents a plan view of the valve seatbetween the compression pump and compression chamber above thecompression pump. It is preferred that the shaft 1 on which the rotor iscarried shall have a single hearing 2 because of its greater simplicityfor lubrication instead of the usual two'bearings. The other end of theshaft from that carrying the rotor 3 bears a crank and crank pm 6, theeccentric of which is proper for the traverse of the pistonactuated bythe connecting rod 7. An air cooled casing 4,.to which is secured astator 5 encloses the rotor 3, shaft 1 and oiling arrangements therefor.

In Fig. 3 will be found the preferred construction, in general terms, ofthe connection between the piston 8 and the connecting rod 7. This isaccomplished not by the usual wrist pin arrangement, but by, providingtwo strongly opposed springs a and b of well tempered steel, theexcursion of which isalways well within the limit of elasticity. Thesesprings are opposed and bear upon a flange or extension 0 of theconnecting rod laterally, as shown, while they are secured firmly intothe interior space of the piston body. In this Way the connecting rodcan swing from side to side, as is needed in making the stroke, and atthe same time, under spring pressure the piston can move slightlylongitudinally to the connect ing rod. This means thatif the piston isopposed by a high pressure in passing up to the head d of the cylinder,the clearance space e in the cylinder will beadjusted to a little largeramount than if the back pressure on the piston f is small. In the heada? of the cylinder are preforations j upon which rests an unperforateddisk or valve 9- having suflicient clearance between its circumferentialedge and the inner wall of the chamber 9 to allow gas to pass by saiddisk or valve into said chamber when the pressure is sufiicient to causethe valve 9 to rise and to lift said disk or valve against thecompressive force of the spring S. It will be seen that by thisarrangement the pum ing is not by a constant traverse of the plston, butone which is shortened somewhat, though to a small degree, by the loadon the apparatus being greater; that is, if the piston has to compress adense gas it can yield somewhat, especially when the back pressure intothe condenser into which it is feeding the gas is higher. On the otherhand, if the gas is comparatively rare and of low pressure or denslty,the clearance space 0 is not so increased by the pressure, but thepiston makes substantially its full stroke without any diminutionwhatever. It is contemplated in the use of the invention that thereshall be a considerable variation in the density of the gas which isbeing pumped, and also in the back pressure of the condensing chamber,especially at the start. The intake openings which feed the gas into thespace above the piston are indicated as a set of openings 72. and h inthe sleeve which are uncovered at the lowest part of the stroke of thepiston. All these openings are fed from the intake pipe or conduit Hther. When the pressure in this condens-' ing chamber becomes veryexcessive, that is, more than a predetermined amount, the valve ismaintained nearl or quite, closed until the pressure falls 0 to a valuebelow that which the pressure of the Spring in the piston can exert,when the valve is again opened and the pressure again builds up to thedesired value. In this way a very desirable automatic regulatingmechanism for the ressure in the system is obtained, and in a dition avery effective regulator providing against in ury to the apparatus byblowing up due to an abnormal increase of pressure which might occur incase of an air leak inwards. This arrangement auto matically regulatesthe untraversed Space so that it is small when the rcssures are low, andmuch larger when t e pressures are hi h.

The piston, when drawn down. leaves a partial vacuum back of it whichfills at once on the uncovering of the openings or passages h and h inthe walls of the cylinder when the end of the piston passes them in itsoutward stroke. These are covered at once on the return stroke andtheonly active valve is the one at the head'of the cylinder, which, in thiscase, may be a flat valve 9 as indicated at Fig. 4. Above the valvethere is glreferabl a slight expansion chamber 9 t e cylin er itselfbeing provided with cooling wings, since the greate the amount of heatwhich can be dissipated at this part of the apparatus, the better willbe the economy. A duct or conduit pipe P leads from the assage 9 over tothe interior of what may be called a condenser or liquefying chamberwithin the shell-10. This consists preferably of a more or lesscylindrical body or shell capped at each end, and in the interior ofwhich have been slipped a. number of hollow tubes say four T and T, etc.or sheet metal flues, so as to increase gradually the interior surface"exposed to the gas. These tubes may be in a group which bear upon theouter sides and bear upon each other, so that good heat conduction maytake place between the outer walls and the inner parts of the structure,and both the shell 10 and inner structures may be made of a goodconducting metal, such as copper. Surrounding the shell 10 and extendingfrom it is a series of fins or wings \V made in good conductive relationthereto, as by tinning or soldering, and these wings or extensions arestaggered circumferentially with relation to one another whereby the airsuccessively flow over the multiple metallic fins and absorb heattherefrom thus cooling the condensed SO; in the multiple tubes andspaced in such a way that they give great freedomto the passage of airupzvards and between and through and a ut them for the removal ofheat orconvection currents. They are very numerous, and while they might beexposed to a current of air wlthout further attention, they arepreferably jacketed by an outer drum in contact with the projections, soto speak, this outer drum being of thin sheet metal of only suchstrength as is necessary to provide air currents as need be, or to allowhandling'without destruction or deformation. This outer drum furnishesor acts as a chimney in its vertical relation, whereby air is drawn inat the base between the projections or wings of the shell 10 anddelivered above in consequence of the fact that the air is somewhatheated in passing the wings or projections, and functions as a chimneydraft. It is, however, preferable to extend this shell upwardly to aheight above the shell 10 maintaining its tightness and makin it actstill more effectively as an up-cast raft chimney, increasing greatlythe flow of heat from the wings or fins into the body of air which isthus actively passing them. It is, of course, presumable that suchchimney may, if it is convenient to do so, be extended at still greaterlength in any ready way, such, for example, as turning the chimneyextension directly into a flue whereby a chimney draft of the ordinarytype is added to the effect before described. This is very desirable,and decidedly effective. As there is no damaging heat concerned in theappliance, the extension of the chimney may be made even of woodextending up towards the roof of a building. These devices effectivelyobviate all necessity for water cooling, which has been a decidedbugbear in many types of refrigerating apparatus. The shell orreceptacle 10 or condenser, as it may be termed, receives from the pumpsulphur dioxide gas only, but at such a pressure that when it loses heatfrom the wings, it condenses into liquid sulphur dioxide, which tricklesdown in the interior, and finally is discharged into a small floatchamber, which has much the structure or appearance of a carburetorfloat valve arrangement employed in gasolene feed for automobiles. Thereis a hollow float 11 connected by a system of levers to a small conicalor needle valve 12 tightly fitted to its seat in the valve box 13. Theleverage connection between the float and thevalve is made so that thefloat moves. say, twelve times as far as the valve will move. This meansthat a slight amount of fluid surrounding the float 11, namely, sulphurdioxide liquid, lifts the float on a certain accumulation having takenplace, and opens the needle valve 12, allowing this accumulation to runthrough the needle valve, thus lowering the level of the liquid in whichthe float exists, and immedlately causing complete closure of the valve.These intermittent feeds of sulphur dioxide liquid pass down into theevaporating chamber or cooler through the pipe 14 which is a tube ofsmall bore, entering into the base of a cooling coil 15. Therefore, ingeneral the arrangement consists of a hollow vessel shown as a s here oflight metal and empty, or a solid ody of very light material may takeits place. The stem of a valve 12 passes through an opening in thecenter of this float body downward, which stem actnates the Valve toopen and close it. The valve is of small dimensions and fits closely toits seat in the ordinary way. The float body in rising will, as is seen,lift the long arms of two levers AA provided with stationary fulcrums,the short arm downwardly extending being linked by a pair of links BB tothe long arm of a second set of levers C-C fulcrumcd in fixed positionfrom the upper cover while the short arm 15 an extension which engagesbetween two discs centering on the valve stem itself at its upper end.Thus an upward movement. of the float. lifts the valve but at a slowerrate than the float itself moves. The float body fits closely thechamber in which it rests, but it is free to rise when liquid comingdown from the condenser above surrounds it and falis to a certain levelin the cup w thin which it rests. The parts are so balanced that thepressure existing normally between the condenser space and theevaporator space below will hold the valve shut until sutiicient. liquidimmersion of the float body has taken place. At this moment the floatbody will have a tendency to rise sufliciently to overcome the pressuredifference which holds the valve shut. On the float rising and openingthe valve, the pressure difi'erence is in part neutralized and the floatover-shoots or rises beyond mere equilibrium, thus permitting a rapidemptying of the space around the float of the liquid accumulatedtherein. The sulphur dioxide refrigerant being of very low viscosity,escapes rapidly as a liquid into the evaporator and the float, a, littlebehind time, comes down and reeloses the valve, but not untilpractically all of the condensed liquid has been discharged. Thisoperation is repeated at intervals. This coil 15 corresponds to theordinary cooler in the refrigerating system exposed by its surface tothe cooling of air or the cooling of water in a refrigerating box. 7

My invention, however, contemplates a further step. in that in normaloperation the coil is submerged in a freczable liquid, such as water,whereby the space surroundcoil and the water interior thereto .will

gradually freeze, as well as the water 19 exterior thereto, and acoating will gradually thicken as the cooling advances, provided thatthere is not a large excess of heat from the, outside tending to keepthe ice melted as fast or faster than it forms.

Should the demand for cooling be continu-- ally lessened, then the icelayer 18 will gradually extend, and it may be conceived at the last asleaving no water unfrozen in the space or box 16. This is the extremecase, for during the process of freezing of the ice layer all over thecoil 15, there comes into play another function; that is, the ice beinga fair non-conductor of heat, the flow of heatas the layer thickens isgradually more and more cut ofl, resulting in an automatic adjustment ofthe heat flow to the coil. or a stoppage of the heat flow to the coilwhen the demand is small, and the storage of the negative heat, or, asone may say, of the cold around the coil. There are at least two resultsof this happening. In the first place, the temperature of the coilitself falls so that the sulphur dioxide in the apparatus willaccumulate there and not be rapidly evaporated, at the same time thatthe pressure on the working pump will fall, since the gas which it getsfrom the evaporator or cooler becomes more and more rare, or approachesmore and more a partial vacuum. while at the same time the effect of thecooling of the condenser 10 goes on a pace and reduces its temperature,and conse quently the back pressure on the pump, thus saving power whenthe load is light, and at the same time saving wear and tear on theapparatus, everything working, as it were, favorably to increaseeconomy. By means of the above mentioned process also supercooling isprevented without the use of thermostatic or pressure controlnecessarily, because the ten'iperature in the refrigerator box can neverfall below the temperature of the freezingliquid. Such liquid may beplain water with a mixture of aslight amount of other substance, thepurpose of such mixture simply being to lower the temperature in the icebox a slight amount below 32 F. when such is desired.

Now, if, at this time, the pump be shut down by shutting off the drivingpower of the motor, there will be an accumulation in throughout thewhole apparatus.

the condenser of substantially all the free sulphur dioxide liquidpossible to exist therein, and there will also be a mass of ice aroundthe cooler .or evaporator coils. In this way, we have secured a storagewhich may continue the refrigerating action of the apparatus for aconsiderable time While it is shut down. As the apparatus rests and heatreaches the tank 16, there will be, of course, a reduction of the amountof ice which is supplanted by water, and later an evaporation of thesulphur dioxide contained in the condenser coils with a fairequalization of pressure If new the starting current is put on themotor, it carries the piston over center and starts to run with verylittle load and an entirely favorable condition, and gradually accumthepump of Fig. 1, the sulphur dioxide vapor. It may be here mentioned thatin Fig. 1, the cooling coil or evaporating coil 15 will have attached toits outer surfaces extensions of the metal in the form of wings or vanes18 for the purpose of extending the action of the cooling coil for adistance outside of its own body. This is, however, best illustrated inFig. 2, in which these extensions, are projections 18, 18, 18, etc.,which may be discs surrounding the chamber 15, or star shaped pieces oreven separate projections attached thereto or otherwise outwardly. Theyvirtually make the outside of the vessel 15 a more extended surface andlessen the intensity of the difference between the outer layers of thesurrounding liquid and the inner layers of ice when frozen. They, inother words, modify the acuteness of the barrier which forms around theinner chamber by the freezing of the surrounding water in the vessel 16,and are capable of being adjusted or regulated by construction to anycircumstances which may be found most favorable to be met, and this mayvary under different applications.

The shaft 1 Fig. 1 is, as it will be seen, oiled by a. set of wickoilers coming up from oil spaces below, as is marked 20. There is littlelubrication needed as a single bearingis used, and it is of such anature as not to demand agreat amount of lubrication. It is desirable toarrange the lubrication drip to be taken up again and be reconveyedcompress pure sulphur dioxide ton yielding increasingl to the bearingafter it has passed through a pieceof felt for filtering.

While many formsofvalve may be suitable, even automatic valves, for theexit valves over the pump cylinder above the piston, a simple valve 9,Fig. 4 may be illustrated as effective for the purpose, which consistsof a flat sheet of substance, such as hard rubber, of small thicknessand preferably internally reenforced by metal bars or wire pressed downby a spring S (shown in Figs. 1 and 3) over a series of holes 7'. Thisvalve has been used with success.

The operation of the device is as follows: The machine is first chargedwith the requisite amount of liquid, the pump is started into operation,the liquid evaporating instantly, and it' is takenup by the pump in theva orized form. Before the liquid is injecte into the machine, however,the ma chine must be exhausted as completely as possible of air in orderthat there will be no air compressed over and over again, which wouldresult in doing work on air, from. which there would be no benefit and 9it would act as a clog. The object is to gas. The gas is then pumped tothe condensing chamber, where the heat of compression is lost externallyby means of the condenser. The 9 gas then liquefies and runs down intothe float valve chamber. When a sufiicient amount of liquid hasaccumulated in this chamber, the needle valve opens and emits a smallquantity of liquid to the evaporator 1 chamber or expansion vessel,which is in the ice box. 01', this evaporator or expansion coil may be aconventional coil of copper pipe, or it may take the form or structureshown in Fig. 2 of the drawings. When 1 the liquid reaches theevaporating coil in turning into a gaseous state, it takes up thenecessary heat to accomplish this transformation from the surroundingmedium. The gas is then returned to the compression pump and the cyclerepeated.

In accordance with the provisions of the patent statutes, I havedescribed the principle of operation of my invention, together with theapparatus which I now consider to represent the best embodiment thereof;

but I desire to have it understood that the apparatus shown is onlyillustrative, and that the invention can be carried out by other means.

What I claim as new and desire to secure by Letters Patent of the UnitedStates is:

1. In a refrigeratorthe combination of a compressor having a springsupported pisas com ression pressure increases to re uce supp y of avolatile refrigerant and reduce the compressed charge under increasingback pressure, a condenser having multiple metallic fins a chimneycarrying air for condensation 1 in amount corresponding to increasedcondenser temperature, controlling means at the outlet of said condensercomprising an automatic intermittent valve, an evaporator receivingrefrigerant periodically in small intion of liquefied refrigerant toform and to retard evaporation of refrigerant at pre- 7 determined lowpressure during a desired the tank in intmate thermal contact withperiod of rest from compression.

3. In a refrigerator a tank for containing a freezable liquid, anevaporator within the tank for evaporating a volatile refrigerant,

a compressor in operative relation with said evaporator, fins of largesuperficial area around the evaporator in close heat conducting relationthereto and within the tank; a condenser, and a valve operatedautomatically under a differential condenser and evaporator pressure topermit feeding of regulable quantities of liquefied refrigerant to theevaporator.

4. A refrigerator having a container for liquefied volatile refrigerant,a water tank surrounding said container, metallic fins in the containerproportioned in area to tank capacity so that in normal operationuncongealed water will always be maintained and a variable thickness ofice, formed according to rest periods from compressor operation, may beelfected to prolong the cold during said rest periods, a compressor, acondenser, and a valve to permit the auto matic feeding at intervals ofsmall quantities of li uefied refrigerant to the evaporating cham erwhereby a definite low temperature may be held substantially constantduring service.

5. A refrigerator containing the following elements assembled; a chamberhaving volatile refrigerant, a pump or compressor supplied from saidchamber and delivering such volatile refrigerant under pressure to acondenser chamber surrounded by extended fins constituting draughtspaces for cool ing air passing over them, an evaporator arranged withan outlet in connection with the intake of the compressor, a tankoutside the evaporator, a body of freezable liquid in said tank,extensions or fins of heat conducting metal on the outside of theevaporator itself, a controller valve, and means to close and open saidvalve automatically and intermittently in passing condensed liquid fromthe condenser chamber or space to the (evaporator.

6. A method of refrigeration consisting in compressing in variablevolume dependent on back pressure of compression a condensible gas oflarge latent heat such as sulphur dioxide, cooling the same toliquefaction, releasing the liquid as needed at suitable pressure forcooling, conveying the cooling effect to a second liquid to form an iceblock allowing a free space for expansion of such liquid by freezing,and by-passing heat through or around the accumulat ing body of frozenliquid to store cold to cover rest periods of functioning andenhancerthe overall efficiency, and also to reduce the temperature dropin regulating supply of gas and liquefaction.

ELIHU THOMSON.

